Resistance element for electric irons



Feb. 13, 1951 c. H. SPARKLIN ETAL RESISTANCE ELEMENT FOR ELECTRIC IRONS 2 Sheets-Sheet 1 Filed April 11, 1945 Feb. 13, c SPARKLIN ET L RESISTANCE ELEMENT FOR ELECTRIC IRONS Filed April 11, 1945 2 Sheets-Sheet 2 flaerfifiij- 671a 7/6 sjfijvariJzkg f ki/z l fj/forg %W W%W Patented Feb. 13, 1951 RESISTANCE ELEMENT FOR. ELECTRIC IRONS Charles H. Sparklin and Philip J. More, Chicago, Ill., assignors to Birtman Electric Company, a corporation of Illinois Application April 11, 1945, Serial No. 587,744

in Charles H. Sparklin application, Serial No.

524.850, filed March 3. 1944 now abandoned.

The invention is illustrated in the drawings, in which Fig. 1 is a plan view of an iron incorporating the resistance element; Fig. 2 is a longitudinal section taken along the line 2-2 in Fig. 1; Fig. 3 is a section taken along the line 33 in Fig. 1; Fig. 4 is a section on line 44 in Fig. 1; Fig. 5 is a plan view of the iron with the element in place but uncovered; Fig. 6 is a detailed View of a portion of the resistance element; Fig. 7 is a sectional view taken along the line 1--'| in Fig. 5; Fig. 8 is a similar section at a later stage in the formation of the element; and Fig. 9 is a detailed view of the refractory plugs at the front of the element.

Since the method of forming the element is substantially the same as that set forth in said application Serial No. 524,850, it will be explained here in less detail.

The iron 10 comprises a sole plate ll of any suitable metal, preferably aluminum or steel. Upon the upper surface of the sole plate are converging integral vertical flanges I2, l3, l4 and which are arranged in pairs and define the slots I6 and H. The flanges thus form a V pointing toward the front of the iron. The slots 16 and H are closed at the rear by walls 18 and I9, respectively, and at the front end by a single wall 20. Each of the rear walls is provided with a circular opening 2! and 22, respectively. These openings are closed by lava plugs 23 and 24, respectively, in which there is a central opening through which the resistance element extends.

The slots i5 and H are joined at the front by a transverse slot 30, within which are mounted the plugs 3i and 32, which are superimposed. One of these plugs is provided with a groove 33 within which the resistance wire may lie.

The plugs 23 and 24 are made from fired lava. These plugs are slightly tapered from the inside to the out and are slipped into place from within the slot, and, once in place, cannot pass through the opening to the outside. They are held in position from the inside by the embedding powder. The pieces may also be made from high heat porcelain.

The front plugs are likewise made of fired lava or the equivalent.

The resistance wire is in the form pf a tape 40 which is coiled upon a ceramic refractory rod 2 Claims. (C1. 219-25) 2 4| which contains a peripheral helical groove 42. As shown, a pair of these rods is employed but a continuous V-shaped rod may be used if desired, in which case a channel will be hollowed out of the sole plate at the front. In the form shown, the tape is doubled over at each end and the free end of the wire carried back through the plug 23 or 24 and passed into an opening 43 in the neck 44 of the ceramic rod; This doubling of the ends of the wire serves to prevent buming out at the leads which otherwise frequently occurs. The wire or tape issues from the opening 43 and passes directly into the helical groove 42. A suitable ribbon for a 1000-watt iron is a Nichrome tape 5 inch wide and 0.008 inch thick. The convolutions of the wire are separated by about 2 inch.

The rods 4| are alike at both ends, there being an opening 45 at the front end through which the tape passes, as shown in Figure 4, to the adjacent rod.

In assembling the element the grooves l6 and I! are filled somewhat more than half full with an embedding powder. This powder is preferably zirconium silicate which is described and claimed in the co-pending application of Philip J. More, Serial No. 588.969, filed April 18, 1945 now Patent No. 2,512,668 dated June 27, 1950. This zirconium silicate comprises a relatively coarse heavy material and an additional portion of very fine material. A preferred embedding powder is sold by Titanium Alloy Mfg. Co, under the name Tam Cement No. 31,568. After the powder has been put into the grooves in weighed amount and distributed uniformly therethrough, it is pressed into the receiving bed 50, as shown in Figure 7.

As shown in Figure '7, the head II of the tool 10 is substantially deeper and. more U-shaped than the corresponding one in case 524,850. This has been found highly desirable since it produces a semi-circular groove having side extensions which serve to locate the rod 4|. When a shallower groove is employed, the rods tend to ex tend'out of the groove and into contact with the sides.

The rods 4| are then laid in position, with the wire" already on them. The plugs 23 and 24 are on theends of the wire and are placed in posi-- tion in the openings 2| and 22. The plug 31 at the front has been dropped into position prior to the addition of the powder, with the groove 33 crosswise of the opening. It will be observed that the metal .is'islightly grooved at 46 to hold the plug 32 in position.

After the rods and wire have been placed in position, the plug 32 is placed in position and then additional powder is carefully distributed on top of them, as shown at 5| in Figure 8. In each case of course the amount of powder is carefully weighed out in advance and it is evenly distributed over the surface. A bar 80 of aluminum or other metal is then placed on top of the slots. This bar is tapered at the sides and the maximum dimension is slightly larger than the corresponding dimensions of the slots, so that the bar must be forced in by pressure, and, once in, is securelyheld within the flanges. These bars are placed in position in the two slots. At the same time a corresponding bar 61 is placed in the transverse slot 30, and then pressure is applied to all three to compact the refractory powder'i-nto the final form shown in Figures 2 and 3.

The usual electric contacts, thermostats, and the like, have not been shown in this application because they are not part of'the present invention. The electric resistance element may be adapted for various purposes. v The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom.

What we claim as new, and desire to secure by Letters Patent, is:

1. An electric iron comprising a metal sole plate having a pair of converging grooves thereon, each defined by a pair of substantially vertical flanges, a wall closing each of said grooves at the diverging ends except for a central opening in the wall, a pressed powdered coherent bed of insulating material in each groove, a coiled resistance wire within the bed of insulating material, and a ceramic refractory plug about said wire in each opening with the plug having its outer end tapered and locked in position in the opening by the pressed powdered insulating material within the groove bearing against said plug, said wire being adapted for connection at each end to a source of electric current.

2. The electric iron of claim 1 in which said vertical flange and said wall are each substantially integral with said sole plate.

CHARLES H. SPARKLIN. PHILIP J. MORE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,147,388 Gold July 20, 1915 1,551,868 Clark et al Sept. 1, 1925 1,997,844 Wiegand Apr. 16, 1935 2,048,614 Myers July 21, 1936 2,222,192 Arnold et a1 Nov. 19, 1940 2,408,886 Scharf Oct. 8, 1946 

